Propane kit for setting mixture, 81 Civic

Posted this in the early Civics forum too, thought I'd try here in case somebody here who knows doesn't read that specific forum:

The service manual for my car says I must use a propane enrichment kit to set the carb mixture. You set the idle, inject propane into the air-intake tube, and set the mixture based on how much the idle RPM rises.

The kit appears to be a long tube attached to a pushbutton and dial operated metering device that in turn attaches to a standard hand-held propane canister.

I can order such a kit online for 55 bucks, and I've heard NAPA will sell you one on special order for around 80. But I am wondering why I cannot simply use an ordinary brass torch nozzle on the propane canister, stick it into the intake tube and slowly release propane that way. This seems logical, yet neither the OEM Honda manual nor Chilton mentions it; both call for the "enrichment kit."

Has anyone set the mixture on these 3bbl Keihin CVCC carbs without using the kit? Has anyone tried injecting propane with the standard brass nozzle?